The present invention relates generally to full functional sting of an integrated circuit die before assembly, and particularly to an IC bond pad arrangement for making both a temporary or test connection and a permanent connection to the die.
There is an interest in performing full functional testing of ICs prior to packaging. This is due in part because of the cost associated with packaging even singular IC devices. However, in addition to singular IC devices there is increased interest in full functional testing of individual IC devices before the individual devices are assembled into multi-chip modules (MCMs).
In one approach to testing before packaging, it has been proposed that an ultrasonic wire bonder using a reduced bond foot size and reduced force can be used to effect a temporary bond that will allow the wire to be removed from the bonding pad, without damage to the bonding pad, by simply pulling the wire from the pad. One possible problem with this approach is that it may be difficult to achieve bonds having a sufficiently uniform low strength. Bonds of uniform strength are necessary so that 1) the wires can be consistently removed by a force that does not break the wire, and 2) the wires do not lift off during wire bonding. If the wire is broken, then a wire stub is left on the pad and this is likely to be objected to by the purchaser of the die and lifted bonds while bonding creat costly reworking. In addition, even if the wire is completely removed, there is some undesirable defacing of the bond pad surface.
Thus a need exists for a bond pad arrangement that provides for a reproducible and reliable temporary wirebond test connection, that allows the wire to be removed, and does not in any way affect the production assembly bond pad.